The U.S. military continues to work with a blacklisted Iraqi special forces unit despite overwhelming evidence that its officers have engaged in human rights abuses for at least two years.

In hours of footage captured by Iraqi photojournalist Ali Arkady, licensed by ABC News and broadcast on World News Tonight with David Muir and Nightline last week, officers of an elite Iraqi unit called the Emergency Response Division (E.R.D.) are shown directing the torture and execution of civilians in Mosul late last year. A U.S. military spokesman said that while an investigation of new evidence of atrocities committed by the E.R.D. is warranted, there is no legal reason the U.S. cannot continue to work with the unit.

The unit had already been blacklisted in March 2015 under the Leahy Act, which requires foreign military units to be banned from receiving U.S. military aid if there is "credible information that such unit has committed a gross violation of human rights.” Top American commanders, however, have continued to praise the successes of the E.R.D. and boast of a "fruitful partnership" between the U.S. military and the unit, including coordinating airstrikes on ISIS.

“The photos are sickening. They clearly depict war crimes,” Sen. Patrick Leahy (D-Vt.), who authored the federal law 20 years ago, said in a statement to ABC News. “That they were brazenly lauded by the unit’s leader suggests that they were far from aberrations. It is my understanding that the United States no longer supports the Iraqi unit involved, but we should insist that the individuals responsible, and particularly the leaders, be prosecuted and appropriately punished. The fact that U.S. military personnel praised the Iraqi unit’s cooperation is deeply disturbing and requires further investigation by the Pentagon.”

A spokesperson for the U.S.-led Operation Inherent Resolve in Baghdad said officials were not previously aware of the atrocities documented by Arkady, and the U.S. military has since contacted Iraqi officials to discuss the incidents exposed by ABC News. The spokesperson also defended, however, the U.S. military’s legal right to work with a unit deemed essential to the campaign to liberate Mosul.

"The Emergency Response Division was disqualified from receiving U.S. equipment and training in March 2015," U.S. Army Col. Joe Scrocca, a spokesperson for the coalition, told ABC News. "Leahy vetting does not prevent the U.S. from working with the E.R.D., as we do with other elements of the Iraqi Security Forces, to help ensure a coordinated effort among different elements of the ISF in the fight to defeat ISIS in Mosul."

A top adviser to Sen. Leahy, however, disagreed, questioning whether the military is adhering to the spirit of the law, given the credible evidence of human rights violations committed by E.R.D. soldiers.

"If we are providing advice or coordinating airstrikes, clearly we are assisting the actions of that unit,” Tim Rieser, senior foreign policy aide to Leahy, told ABC News on Tuesday. “One of Senator Leahy's purposes in writing the law was to prevent the U.S. from being associated with or implicated in the actions of those who the law is intended to address.”

Sarah Leah Whitson, Middle East executive director at Human Rights Watch, who has worked in Iraq since 1991, agrees.

“The U.S. government is playing a clunky shell game, pretending to move its assistance away from abusive Iraqi units like the E.R.D., while still working with them, training them and coordinating with them," Whitson said. "The bottom line is that the U.S. is dangerously close to complicity in the disgusting torture and violence these forces are perpetrating on Iraqi citizens, and in reality, ensuring that the fight in Iraq will not be ending any time soon.”

At a Pentagon press briefing in January, U.S. Army Col. Brett Sylvia, then the commander of Task Force Strike in Baghdad, told reporters that American officers had recently advised the E.R.D. and called them "a very effective fighting force."

This month, even as officers at Operation Inherent Resolve were responding to questions raised by ABC News in its investigation of Arkady's footage, a top U.S. commander in Iraq tweeted praise for the Emergency Response Division.

"Watch the #Iraqi ERD send a message to #ISIS on #saturdaymorning in Western #Mosul," tweeted U.S. Army Maj. Gen. Joseph Martin on May 13, with a link to a battlefield video on the E.R.D.'s official Facebook page showing the Iraqi troops in combat.

Despite the ban, the E.R.D. was also included in the latest request to Congress for millions of U.S. taxpayer dollars for the Iraq Train and Equip Fund in March. Scrocca claims that request was merely designed "to keep options open in the event E.R.D. … overcame Leahy vetting issues.”

"Requesting funding for such a unit, when there's been no action to hold people accountable, sends the wrong message," Rieser countered.

Col. Ryan Dillon, another spokesman for Operation Inherent Resolve, was asked during a phone briefing on Thursday how the E.R.D. has continued to use U.S. equipment and weapons, such as anti-tank launchers, despite the Leahy ban.

"So we do not equip them but as you've seen we do equip other elements of the Iraqi Security Forces,” Dillon said. “Any time we see any weapons in the hands of those units or elements that should not have it we address it with the Iraqi Security Forces and make steps to keep that from happening in the future. They should not be in the hands of those that do not pass our vetting process."

Whether the soldiers themselves will be held accountable for their actions remains unclear.

According to an E.R.D. officer, the U.S. military convened a meeting earlier this month with the E.R.D. soldiers who were to be named in the ABC News report. Scrocca confirmed that several such meetings took place with Iraqi officials, including representatives from Prime Minister Haider al-Abadi's office.

Iraq's Ministry of Interior said last week it "ordered the formation of an investigation committee" to look into the reports and "encouraged the investigators to conduct an honest and clear investigation."

Iraqi officials told ABC News they have recalled all the officers implicated in the investigation from the field and dispatched a team of medics and social workers to the neighborhoods to interview victims' families.

Though he had already confirmed much of ABC News’ reporting in an extraordinary on-camera interview, E.R.D. Capt. Omar Nazar attempted to refute some of the allegations in a 10-minute video posted to YouTube last week. Dressed in civilian clothes, Nazar asked a man who was shown being tortured in the footage about being abused by an E.R.D. intelligence team led by a different officer.

"You guys took me for interrogation, just interrogation, and you roughed me up. I don’t have any health issues, it was just an interrogation, I wasn’t hurt badly," the man says, with Nazar at his side. "My sons joined ISIS. One of them blew himself up, the other turned himself in, that was their choice. They took their own path, but I don’t have any problem with you guys. My life has been much better since the liberation."

Several experts told ABC News that the sectarian violence against Sunni Muslim civilians in Mosul depicted in Arkady's videos is a major reason why ISIS captured Mosul so easily in 2014, so U.S. support for the E.R.D. — which has ties to Iran’s espionage service, the Iranian Revolutionary Guard Corps, the strongest U.S. adversary in the region — might be counterproductive.

"Partnering with clearly sectarian forces backed by a radical and often sectarian state like the Islamic Republic of Iran, only helps fuel Anti-American extremism,” said Phillip Smyth, an expert on the militias and Iran at the Washington Institute for Near-East Policy, “and gives more reason for distrust, if not hatred for the U.S. within some Sunni communities.”

Ali Khedery, the longest-serving U.S. diplomat in Baghdad who also advised three commanders of U.S. Central Command, told ABC News that the U.S. is just supporting one bad actor instead of another.

"It is strategic folly,” Khedery said, “for the U.S. to attempt to defeat ISIS -- a terrorist group -- by backing another band of terrorists.”